5 noble fir and 3 douglas fir = $ 420
12 noble fir and 9 douglas fir = $ 1080
Let noble fir be n, and douglas fir be d.
5n + 3d = 420 ..............(i)
12n + 9d = 1080 ...............(ii)
Multiply equation (i) by 3.
3*(5n + 3d) = 3*(420)
15n + 9d = 1260 .............(iii)
Equation (ii) minus (iii)
(12n + 9d) - (15n + 9d) = 1080 - 1260
12n - 15n + 9d - 9d = -180
-3n = -180
n = -180/-3 = 60
Substitute the value of n in (i) 5n + 3d = 420
5*(60) + 3d = 420
300 + 3d = 420
3d = 420 - 300 = 120
3d = 120
d = 120/3 = 40
Therefore Noble fir tree cost $60 while Douglas fir tree cost $40
Step-by-step explanation:
let no. of hours be x.
45x - 12 ≥ 117
45x ≥ 129
x ≥ 2.8667 (5sf)
therefore, 3 hours (round up to next whole number).
Topic: inequalities
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Answer:
D.
Step-by-step explanation:
The solution is where the lines intersect which is at the point (3,2).
So the answer is Option D.
The point (3,2) satisfies both equations.
Total tickets sold = 800
Total revenue = $3775
Ticket costs:
$3 per child,
$8 per adult,
$5 per senior citizen.
Of those who bought tickets, let
x = number of children
y = number of adults
z = senior citizens
Therefore
x + y + z = 800 (1)
3x + 8y + 5z = 3775 (2)
Twice as many children's tickets were sold as adults. Therefore
x = 2y (3)
Substitute (3) into (1) and (2).
2y + y + z = 800, or
3y + z = 800, or
z = 800 - 3y (4)
3(2y) + 8y + 5z = 3775, or
14y + 5z = 3775 (5)
Substtute (4) nto (5).
14y + 5(800 - 3y) = 3775
-y = -225
y = 225
From (4), obtain
z = 800 - 3y = 125
From (3), obtain
x = 2y = 450
Answer:
The number of tickets sold was:
450 children,
225 adults,
125 senior citizens.
